The present invention relates to semiconductor workpiece position sensors and methods of monitoring the position of a semiconductor workpiece.
The fabrication of semiconductor devices includes a plurality of processing steps. Individual devices are formed from die from a semiconductor workpiece such as a wafer. Typically there are four general categories of operations performed on a semiconductor wafer during the fabrication process. Such operations include layering, patterning, doping and heat treatments.
Layering provides thin layers to the surface of the semiconductor wafer. Patterning provides removal of selected portions of added surface layers. Doping of the semiconductor wafer is the process of applying specific amounts of dopants in the wafer surface through openings in the surface layers. Heat treatments of the semiconductor wafer involve operations in which the wafer is heated and/or cooled to achieve specific process results.
Numerous processing devices have been developed to implement the described processing steps of the semiconductor workpiece fabrication process. Depending upon the particular function of the workpiece and the processing device, various configurations are provided. Some conventional semiconductor workpiece processors utilize a semiconductor workpiece holder and a process bowl or container for implementing process steps such as plating. etching, etc.
The typical purpose of providing the workpiece holder and a process bowl is to enable the contacting of appropriate portions of the semiconductor wafer with a processing fluid held within the process bowl. General concerns during the fabrication process include directing the process fluid to the appropriate portions of the semiconductor wafer. Conventional semiconductor workpiece processors have utilized various techniques to shield the various portions of the semiconductor wafer which are not to be contacted by the process fluid. Examples of such conventional systems include applying tape to the back side of a semiconductor wafer to prevent process fluid from contacting the covered portions. Other configurations disclose holding the semiconductor workpiece with a suction cup arrangement to prevent fluid from coming in contact with the back side of the semiconductor wafer.
Although such conventional operations adequately fulfill the purpose of preventing process fluid from coming in contact with the back surface of the semiconductor wafer, other associated problems with the conventional systems still exist. For example, additional process steps are required including applying tape or covering the back surface of the semiconductor workpiece. Further, the semiconductor workpieces are fragile and care must be taken not to damage the wafer during covering of a surface of the wafer.
Therefore, a need exists to implement the semiconductor workpiece processing steps and control the application of process fluid to preselected portions of the semiconductor workpiece without the associated problems typically present in conventional semiconductor workpiece processors.